Italian Prime Minister Silvio Berlusconi has the well-groomed image of a Latin charmer.

But his pledge not to indulge in sex until the general election on 9 April may put the stallion stereotype on hold.

Abstinence from sex is an oath more commonly taken by professional athletes who want to ensure a good performance.

Or by high-moral American teens who stress there will be no sex until they are married.

It is not clear whether Mr Berlusconi's bout of self control, declared on the hustings, is intended to focus the mind or the body. But abstinence, from sex in particular, could have implications for both.

Downhill deterioration

Studies have shown that for men - more specifically for sperm - the type of three-month abstinence promised by Mr Berlusconi can have a negative effect.

If you give up for a couple of weeks, it's not going to make much difference, if you give up for five years, it will

Dr Allan Pacey is a senior lecturer in andrology (male reproduction) at the University of Sheffield and secretary of the British Fertility Society.

"The perception is that if a man abstains for a long time, he'll improve his fertility," he says. "That's true to a point - five days - but beyond that things start to go downhill a bit."

"The longer the sperm hang around in the male reproductive tract, they begin to degenerate, die, and release free radicals, which will then damage other sperm.

"It's a chain reaction - the fresh sperm coming down the tubes enter an environment of free radicals and get damaged."

In the next three months, not just will power will be tested. There are other physiological effects, outside of fertility.

Use it or lose it

Dr Roy Levin, biomedical scientist, describes what abstaining from sex could do to the cardiovascular system - something middle-aged men are encouraged to consider as part of maintaining a healthy lifestyle.

"It's not a fantastic exercise, but for people who don't have any, it will help to maintain their cardio and respiratory functionality.

"If you give up for a couple of weeks, it's not going to make that much difference, if you give up for three, four, five years, it will."

Sportsmen must balance gains and losses in fatigue and aggression

Like much of the body, the sex organs in men and women present a "use it or lose it" scenario. In endocrinology, the production of hormones oxytocin and prolactin - which occurs during sex - will also be reduced.

The effect on mood is hard to gauge scientifically, he says. The effect on the mind, the psychological impact, has also proved difficult to measure.

Sports men and women have made headlines for not having sex for the sake of their jobs.

Team and individual competitors, in football, track, boxing, rugby, have worried whether sex reduces their performance in the field.

There are two key issues, says sports psychologist Matt Jevon: aggression and fatigue.

"In a lot of sports you need fairly high levels of aggression and mental arousal to perform effectively," he says.

Self-inflicted

The parallel with politics in the run-up to an election is quite clear, he says.

"They are environments where people work long hours and are involved in a range of issues they have to keep track of."

To perform at 100% capacity, they must make a positive choice on abstinence, and not be worn out or distracted by the option they take.

If an alien landed on earth, they would think the only thing we do is have sex

Dr Petra BoyntonSex psychologist

Away from lurid Premiership football tales, sex can prove beneficial. On his anecdotal evidence, sex can temper an over-aggressive player.

Wives and girlfriends flew out to the England rugby team ahead of their 2003 World Cup victory. Studies have shown better track performance in post-orgasmic female runners.

With any self-denial, the psychological effect depends on whether it is voluntary, or set through cultural norms, pressure or laws, sex psychologist Dr Petra Boynton believes.

Abstinence campaigns can bring guilt, anxiety and frustration, make people afraid of sex and elevate its importance.

Election smiles

Today, people are obsessed with sex - who's doing it, how often, how well. As a result, she says, unclouded research on abstention is rare.

"If an alien landed on earth, they would think the only thing we do is have sex," she says.

And, she believes, our view of what constitutes sex is too rigid. In reality, couples who abstain in one way may adopt a different, and equally happy approach.

While Mr Berlusconi's pledge to the voters may have come as a surprise to Mrs Berlusconi, but she predicts: "Maybe she'll be smiling come election time and we'll be wondering why that is."